My students have been struggling with number lines. I needed a big activity for them to really grasp the concept especially when you add decimals to it. Those tenths and hundreths are really tricky. I decided to use my floor as a giant number line. You can make it really easy using painter's tape or washi tape. For my students to be interactive with it, I used index cards that had various numbers on them. Examples would be: 1, 14, 7, 3.4, 2.09, etc I would start the students off by saying the first tick mark is 1 and the last one is 3. Then, using the correct index cards that I made. 30 students would place them on the correct mark on the number line. I repeated these steps using the tenths and hundreths place. You can vary this activiy in so many ways to meet the needs of your students. For an extenstion activity, do not give them the first mark, allow your students to create their own number line with the cards you created. Or allow the students to create the numbers on the index cards. A few times I would call out a number then the students would have to race to find it. This was their favorite part with it. This activity was a great eye opener about number lines for my students.